GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Fuel Pump

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See Figures 1, 2, 3 and 4

The fuel pump is the single action AC diaphragm type. Two types of fuel pumps may be found on these vehicles; serviceable and non-serviceable. The serviceable type was original equipment used on all 1964 and 1965 engines, 1966 in-line engines without the AIR emission control system, and 1966 282 and 327 V8s. All other engines were equipped with the non-serviceable type.

The pump is actuated by an eccentric located on the engine camshaft. On inline engines and on the 231 V6 engine, the eccentric actuates the pump rocker arm directly. On V8 and the 200 V6 engines, a pushrod between the camshaft eccentric and the fuel pump actuates the pump rocker arm.



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Fig. Fig. 1: Fuel pump mounting-inline 6-cylinder engine



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Fig. Fig. 2: Fuel pump mounting-229 V6 engine

TESTING THE FUEL PUMP



The fuel pump should always be tested on the vehicle. The larger line between the pump and tank is the suction side of the system and the smaller line, between the pump and carburetor is the pressure side. A leak in the pressure side would be apparent because of dripping fuel. A leak in the suction side is often only noticed from the reduced volume of fuel delivered to the pressure side. However, fuel may leak out on the suction side when the engine is off.

  1. Tighten any loose line connections and look for any kinks or restrictions. Inspect rubber hoses for cracks or leaks and replace if necessary. Inspect the fuel filter for clogging and clean or replace it as necessary.
  2.  
  3. Disconnect the fuel line at the carburetor. Disconnect the distributor-to-coil primary wire or, on HEI systems, the distributor connector. Place a container at the end of the fuel line and crank the engine a few revolutions. If little or no gasoline flows from the line, either the fuel pump is inoperative or the line is plugged. Blow through the lines with compressed air and try the test again. Reconnect the line.
  4.  
  5. Attach a pressure gauge to the pressure side of the fuel line using a Tee fitting.
  6.  
  7. Run the engine and note the reading on the gauge. Stop the engine and compare the reading with the specifications listed in the Tune-Up Specifications chart located in Engine Electrical of this guide. If the pump is operating properly, the pressure will be as specified and will be constant at idle speed. If pressure varies sporadically or is too high/low, the pump should be replaced.
  8.  
  9. Remove the pressure gauge, then reconnect and secure all fuel lines.
  10.  



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Fig. Fig. 3: Fuel pump mounting-231 V6 engine



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Fig. Fig. 4: Fuel pump mounting-V8 engines

REMOVAL & INSTALLATION



See Figures 5, 6, 7, 8, 9, 10 and 11

When you disconnecting or connecting the fuel pump outlet fitting, always use 2 wrenches to avoid damaging the pump.

  1. Disconnect the fuel intake and outlet lines at the pump. Be sure to plug the pump intake line in order to prevent system contamination or excessive fuel loss.
  2.  
  3. On small block V6 and V8 engines, remove the upper bolt from the right front mounting boss. Insert a longer bolt ( 3 / 8 -16 x 2&inch;) in this hole to hold the fuel pump pushrod up and out of the way.
  4.  
  5. Remove the two pump mounting bolts and lockwashers; then remove the pump and its gasket from the engine.
  6.  
  7. If the rocker arm pushrod is to be removed from equipped V6 or V8 engines, remove the two adapter bolts and lockwashers, then remove the adapter and its gasket for access to the pushrod.
  8.  

To install:
  1. Thoroughly clean the gasket mating surfaces of all old material or sealer.
  2.  
  3. If removed, install the pushrod, then install the adapter using a new gasket and secure using the retaining bolts.
  4.  
  5. Coat the mating surfaces with a suitable sealer, then install the fuel pump assembly using a new gasket.
  6.  

On vehicles equipped with a pushrod to actuate the fuel pump rocker arm, if a bolt was not used to secure the pushrod it may interfere with pump installation. A small screwdriver or thin plastic tool may be used to hold the pushrod up and out of the way while the fuel pump is installed. Make sure the pump rocker arm is properly located under the pushrod. Another method of retaining the pushrod it to pack it into position using grease, though this will only work on a cold engine

  1. Install the fuel pump to the engine using a new gasket
  2.  
  3. Install and tighten the pump retaining bolts.
  4.  
  5. If applicable, remove the bolt retaining the pushrod out of the way and reinstall the original bolt to the mounting boss.
  6.  
  7. Remove the plug, then connect the fuel tank line to the pump.
  8.  
  9. Using a backup wrench to protect the pump housing, install and tighten the outlet line to the pump.
  10.  
  11. Start and run the engine, then check for leaks.
  12.  



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Fig. Fig. 5: Release the clamp tension, then reposition it back on the fuel tank hose



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Fig. Fig. 6: Using a backwrench to prevent housing damage, loosen the outlet pipe fitting



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Fig. Fig. 7: Disconnect the fuel tank line from the pump



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Fig. Fig. 8: With the fitting loosened, carefully unthread the outlet pipe from the pump housing



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Fig. Fig. 9: Loosen and remove the pump retaining bolts



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Fig. Fig. 10: Remove the pump from the engine mounting surface



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Fig. Fig. 11: On models so equipped, it will be necessary to hold the pushrod so the pump rocker arm may be positioned beneath it during installation

 
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